1. Field of Invention
This invention relates to windsurfing apparatus and is particularly directed to an improved spreader for use in windsurfing.
2. Prior Art
The sport of windsurfing involves a board which is similar to a surfboard but has a mast pivotally secured thereto with a sail carried by the mast and having a so-called .cent.wishbone" boom pivotally secured to the mast and extending rearwardly along both sides of the sail to join aft of the luff edge of the sail. Originally, the user would stand on the board and raise the sail by lifting the mast to a generally upright position. As wind filled the sail, the user would use his weight to hold the sail upright against the action of the wind and would control the direction of movement of the board by pulling on the forward or rearward portions of the boom. However, the effort required to accomplish this was substantial and placed considerable strain on the user's back and arm muscles. To reduce this strain, the prior art has proposed providing a generally U-shaped harness line secured to the boom, together with a relatively rigid bar strapped to the user and having a hook for slideably engaging the harness line. These devices, called "spreaders", greatly reduce the effort required to engage in windsurfing and have contributed significantly to the rapidly growing popularity of the sport. Unfortunately, sheeting of the harness line, during movement of the boom to provide directional control of the sail and board, causes the harness line to drag across the hook which causes considerable chaffing and wear of the harness line. This required frequent replacement of the harness line which is expensive and, if breakage should occur while sailing, could cause the user to undergo a fall in a possible dangerous location. Furthermore, the effort required to sheet the harness line is increased significantly by the friction across the hook which rapidly produces fatigue in the user. To avoid this problem, some spreader bars have been provided having rollers replacing the hooks to allow the harness line to move more freely. This permits faster sheeting and greatly decreases the effort required to perform the sheeting operation. Also, with the spreader bar hooks of the prior art, high winds may make it extremely difficult to disengage the harness line from the hook and may prevent the user from releasing the sail, when desired, which may have hazardous consequences. This problem, also, is greatly reduced by the use of rollers.
Although spreader bars greatly reduce the strain which the windsurfer must bear physically, this strain must be absorbed by the spreader bar itself. Consequently, the spreader bar must be formed of material which is very light in weight and which is strong enough to withstand these strains and must be sufficiently rigid to maintain its shape despite the stresses that are applied to the spreader bar. On the other hand, the spreader bar must also be sufficiently flexible to provide a shock absorbing function, since the sudden application of such heavy stress loads directly to the surfer's anatomy could cause serious and possible permanent injury. None of the prior art spreader bars have provided this combination of strength, rigidity and flexibility.
A search in the United States Patent Office has revealed the following:
______________________________________ U.S. Pat. No. INVENTOR ISSUED ______________________________________ 4,112,865 P. Carn Sep. 12, 1978 4,630,563 S. Pertramer Dec. 23, 1986 4,712,498 R. B. Oser Dec. 15, 1987 4,741,280 W. Mauderer et al May 3, 1988 4,763,591 D. Taylor Aug. 14, 1988 4,934,297 I. Long Jun. 19, 1990 ______________________________________
Each of these references discloses a windsurfing spreader bar having a hook or roller for retaining the harness line of a windsurfing board. However, none of these references suggest a spreader bar formed of a material which is very light in weight and which is strong enough and rigid enough to withstand the stresses of windsurfing, yet which is sufficiently flexible to provide a shock-absorbing function to prevent injury to the surfer. Thus, none of the prior art windsurfing spreaders have been entirely satisfactory.